Box-shaped ducts are extensively used in heating and ventilating systems to distribute heated or cooled air throughout a structure. The ducts are commonly formed in sections of predetermined length, which are then connected to form a continuous air distribution duct. The material from which the duct sections are formed is sheet metal of the desired gauge fed from a roll or coil of material. As the sheet metal uncoils, it is flattened or straightened to remove the curved set in the material that exists from it being coiled. The sheet metal is then notched along its side edges at predetermined distances where the corners of the duct section will be formed. A shear then cuts the material into blanks of a length necessary to form a finished duct section. This notched blank is then moved 90 degrees onto a roll former to form the male and female portions of a lock seam at the opposite ends of the blank. The blank is then transferred once again, usually 90 degrees, into a roll former to form the flanges that will provide for connection of the individual duct sections. When the flanges have been formed, the blank is then transferred to a sheet metal break where three 90 degree bends are made to form the box-shaped duct section.
As will be readily appreciated, transferring the material both longitudinally and sideways from station to station to form the lock seams and flanges requires a considerable amount of floor space for the equipment, conveyors and transfer tables between the stations. Often times, therefore, large spaces are needed to accommodate the width of existing duct fabricating machines, which increases overhead operating costs.
There is therefore a need for an improved method and apparatus for forming duct sections which minimizes the amount of floor space required to carry out the complete forming process, and which provides for the forming of duct sections more quickly and efficiently and at a lower cost as compared to existing apparatuses.